I received mine last week, it's very well made overall, it fits perfectly and the foam keep the Helix in place.
I was hesitating with the line 6 backpack, because Helix + case= 13kg but I picked the case and have no regret. I was planning to have everything I need (cables, tools...) in the bag but total weight would've been too much.
There's a 9 cm gap on the front so I can add a couple of pedals if I need (MXR size, a Boss could fit with flat plug cables I guess).